1. Field of the Invention
The present invention relates to a method of lining up or positioning micro-balls on a jig, the micro-balls to be formed into bumps disposed on a work for a substrate, chip, or so forth, in a micro-ball mounting apparatus of a semiconductor device manufacturing system, and particularly, to a method of lining up micro-balls on an arraying jig by feeding the micro-balls into array holes on the arraying jig having a plurality of the array holes.
2. Description of the Related Art There has already been disclosed in Japanese Patent Laid-Open No. H7-153765, and Japanese Patent Laid-Open No. H7-153766 a micro-ball mounting apparatus for mounting micro-balls on a work for a substrate, chip, or so forth, wherein an adsorption jig in a sheet-like shape is provided with a plurality of adsorption holes disposed so as to correspond to positions of electrode pads formed on a work, and a group of micro-balls in number corresponding to at least one feed thereof for the work are caused to be adsorbed to the respective adsorption holes, so that the micro-balls adsorbed to the adsorption jig are bonded to the electrode pads on the work.
As shown in FIG. 14, an adsorption unit of this type is provided with an adsorption head 1 which can be moved up and down by a hoisting and lowering mechanism (not shown), and the adsorption head 1 has an adsorption jig 2 in a plate-like shape, provided with a plurality of adsorption holes 2a for vacuum-adsorbing micro-balls which are fluidized and floated.
Further, as shown in FIG. 15, when sucking operation is performed by use of a suction unit (not shown) with the adsorption head 1 already lowered by the hoisting and lowering mechanism, and brought in close proximity to the micro-balls B contained in a stock dish 3 made of metal, installed in the lower part of the adsorption unit, the micro-balls B are vacuum-adsorbed to the adsorption holes 2a of the adsorption jig 2.
With the adsorption unit of this type, the adsorption holes 2a formed in the adsorption jig 2 have a very small diameter, and consequently, air has little fluidity away from the adsorption holes 2a. Accordingly, the stock dish 3 containing the micro-balls B is caused to undergo vibration by use of a vibration generator 4 such as a parts feeder or the like, and the the micro-balls B are sent flying as far as the vicinity of the adsorption holes 2a, thereby enhancing adsorbability thereof. That is, the stock dish 3 provided with the vibration generator 4 serves as ball feeding means for carrying the micro-balls B to the adsorption holes 2a.
Now, the adsorption unit described above is to cause the micro-balls B to be floated through vibration of the stock dish 3 with the use of the vibration generator 4, however, this is not a case where the micro-balls B are sent flying towards all of the adsorption holes 2a at a uniform density. Accordingly, there is a risk that an excessive number of the micro-balls B are adsorbed to some of the adsorption holes 2a on one hand, and none of the micro-balls B is adsorbed to some of the adsorption holes 2a on the other hand.
Furthermore, when the adsorption head 1 sucks in the micro-balls B out of the stock dish 3, and holds the same, one each of the micro-balls B is desirably held by the respective adsorption holes 2a. However, it has been observed that an excess of the micro-balls sticks between the adjacent micro-balls B normally held by the adsorption jig 2, or the excess of the micro-balls sticks to the micro-balls B themselves normally held by the adsorption jig 2, in a condition resembling hanging icicles.
For that reason, it has been in practice that one each of the micro-balls B is fed into the respective adsorption holes 2a of the adsorption jig 2 by use of a filter for removal of the excess of the micro-balls B, provided with holes, each large enough to allow only one of the micro-balls B to pass therethrough, formed at positions corresponding to the respective adsorption holes 2a of the adsorption jig 2. However, this will require a complex mechanism for aligning the adsorption jig 2 with the filter for removal of the excess of the micro-balls B.
Taking into consideration the problem described above, the inventor has developed a system wherein with the use of a ball feeding unit having an arraying jig provided with array holes to which the micro-balls B are adsorbable, formed at positions corresponding to the respective adsorption holes 2a of the adsorption jig 2, the micro-balls B are lined up opposite to the array holes formed in the arraying jig of the ball feeding unit to enable the micro-balls B in the arraying jig to be delivered to the adsorption jig 2. With the system, the micro-balls B can be adsorbed efficiently one by one to the respective adsorption holes 2a of the adsorption jig 2.
Even with this system, however, there have been cases where the excess of the micro-balls B is stuck to the array holes of the arraying jig, so that the micro-balls B are excessively fed to the adsorption holes 2a of the adsorption jig 2, and adsorbed thereto.